Method of making a composite button of an electrical device

ABSTRACT

A composite button of an electrical device has a frame body (1) with a through bore that terminates at openings, and a button portion (2) with a pressing portion (3) extended through the through bore and a flange portion (4) fused to the frame body (1). A silicone resin layer (5, 24) is interposed between the frame body and the flange portion, and surrounds one of the openings. A method of manufacturing a composite button of an electrical device by molding a frame body, forming a silicone resin layer on a surface of the frame body, and simultaneously molding a button portion to a predetermined shape while fusion boding areas of the button portion contacting the frame body.

BACKGROUND OF THE INVENTION

This invention relates to a composite molded product comprising aplurality number of different materials, particularly to a compositemolded product which can be used as a button of electric devices and amethod of manufacturing the same.

A composite molded product in which a thermoplastic resin material and athermoplastic elastic material are joined has been utilized for, as abutton of electric devices such as a portable telephone, a personalcomputer, etc. This composite molded product comprises a frame bodycomprising a thermoplastic resin material and a button portioncomprising a thermoplastic elastic material, and a movable pressingportion and a flange portion joining to the frame body are provided atthe button portion.

Such a composite molded product has been manufactured by fusion bondingthe thermoplastic resin material and the thermoplastic elastic materialin a mold using a two-color molding machine.

However, in the conventional composite molded product used for a button,the contacting surface of the thermoplastic resin material and that ofthe thermoplastic elastic material are all joined so that it maysometimes cause disadvantages. Such a problem is that deflection at theflange portion of the button portion is little whereby stroke at thepressing portion cannot be made large.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a composite moldedproduct suitable for the use of a button of electric devices and amethod of manufacturing the same.

In order to accomplish the object, the composite molded product of thepresent invention has a constitution that a frame body and a buttonportion are joined. Also, the button portion has a pressing portion soprovided in a through hole of the frame body as to freely movable and aflange portion which is to be fused to the frame body. A thin film layeris provided at adjacent to the opening of the through hole, and theframe body and the button portion are not joined to the region at whichthe thin film is formed. The frame body can be formed by a thermoplasticresin, the button portion a thermoplastic elastic material and the thinfilm layer a silicone resin.

Also, the method of manufacturing the above composite molded productcomprises the steps of (a) molding a frame body comprising, for example,a thermoplastic resin, by a first mold; (b) forming a thin filmcomprising, for example, a silicone resin, on the surface of the framebody, and (c) fusion bonding a button portion comprising, for example, athermoplastic elastic material, by a second mold, onto the surface ofthe above frame body at which the above thin film layer is formed andmolding it to a predetermined shape.

The step of molding a thermoplastic resin by the first mold and the stepof forming a thin layer film on the surface of said frame body of thethermoplastic resin molded product may be carried out simultaneously.Also, for formation of the silicone resin layer, it may be employed amethod in which a thin layer film previously printed on a film istransferred onto the thermoplastic resin.

In the above composite molded product, at the contacting surface of theframe body comprising a thermoplastic resin material and the flangeportion comprising a thermoplastic elastic material, the silicone filmlayer is partially provided as a thin layer which is subjected to fusionbonding to the thermoplastic resin but not fusion bonding to thethermoplastic elastic material. At the portion in which the siliconeresin layer is formed, the frame body and the flange portion are notsubjected to fusion binding so that the flange portion is markedlydeflected whereby stroke at the pressing portion can be made large.

Also, by simultaneously carrying out molding of the thermoplastic resinand transfer of the silicone resin layer from the film to which thesilicone resin layer is previously printed, the composite molded productcan be manufactured with extreme effectiveness in bulk-production.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionwhen taken with the accompanying drawing in which:

FIG. 1 is a perspective view of a molded product to be used for theconventional button switch of an electric device;

FIG. 2 is a sectional view of a molded product to be used for theconventional button switch of an electric device;

FIG. 3 is a sectional view showing an example of the composite moldedproduct of the present invention;

FIG. 4 is a drawing showing a first metal mold and a film to which asilicone resin layer is printed of the present invention;

FIG. 5 is a plan view of a film to which a silicone layer is printed;

FIG. 6 is a sectional view showing the steps of molding of athermoplastic resin and transfer of a silicone resin layer;

FIG. 7 is a sectional view showing a thermoplastic resin molded productto which a silicone resin layer is transferred, which is provided to asecond mold; and

FIG. 8 is a sectional view showing the step of molding a thermoplasticelastic material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, a conventional composite molded product comprising athermoplastic resin and a thermoplastic elastic material is explained.FIG. 1 is a perspective view of the conventional composite moldedproduct. At a frame body 41 comprising a thermoplastic resin, a throughhole is formed. Also, a button portion 42 comprising a thermoplasticelastic material has a flange portion 44 and a pressing portion 43. Theflange portion 44 is joined to the frame body 41 and the pressingportion 43 is provided at the through hole of the above frame body 41.FIG. 2 is a sectional view of the composite molded product shown inFIG. 1. The contacting surfaces of the flange portion 44 to the framebody 41 is completely joined.

As can be seen from FIG. 2, in the conventional composite moldedproduct, the contacting surfaces of the flange portion 44 and the framebody 41 are all subjected to fusion bonding so that only a little strokecan be obtained when the pressing portion 43 is pressed. However, whenthe composite molded product is used as a button for electric devices,it is desired to obtain a large stroke.

Next, an example of the composite molded product of the presentinvention is explained. FIG. 3 is a sectional view of an example of thecomposite molded product according to the present invention. A framebody 1 having a through hole at the center portion and a flange portion4 of a button portion 2 are subjected to fusion bonding. However, asilicone resin layer 5 is formed at a region adjacent to the opening ofthe through hole which is at the joining portion of the frame body 1 andthe flange portion 4. The silicone resin layer 5 can be subjected tofusion bonding to the frame body 1 comprising a thermoplastic resin butnot subjected to fusion bonding to the flange portion 4 comprising athermoplastic elastic material. Therefore, when the pressing portion 3is pressed, the flange portion 4 is markedly deflected whereby a largestroke can be obtained. Thus, the composite molded product shown in FIG.3 sufficiently acts as a button for electric devices.

In this example, as a thermoplastic resin, a polycarbonate resin, ABS(acrylonitrile-butadiene-styrene copolymer) resin, etc., can be used.Also, as a thermoplastic elastic material, a styrene series elastomer,ethylene series elastomer, etc., can be used. The composite moldedproduct may have any size depending on the kinds of electric devices tobe applied.

Next, an example of manufacturing method of the composite molded productaccording to the present invention is explained.

FIG. 4 is a sectional view of a first mold 20 for molding a framebody 1. This mold comprises a fixed mold 11 and a movable mold 12. Themold is usually made of a metal, but a material such as ceramic may beused. Between these molds, a film 23 to which a silicone resin layer 24is printed is provided. The film 23, may comprise, for example, apolystyrene, etc., set to a delivery roller 21 and a wind roller 22, andtransfers between the molds 11 and 12 by way of rotation of the rollers21 and 22.

The silicone resin layer 24 is previously printed with a ring shape onthe film 23 as shown in FIG. 5. Also, an inside portion of the ringshape of the silicone resin layer 24 printed on the film 23 ispreviously blanked. An inner diameter of the ring shape substantiallycorresponds to the diameter of the through hole of the frame body 1 ofthe composite molded product. Thus, the silicone resin layer 24 isprovided adjacent to the peripheral of the opening of the above throughhole.

When the inside of the ring shape of the silicone resin layer 24 printedon the film 23 is not blanked, a printed position and a shape of thesilicone resin layer 24 are previously adjusted so that the siliconeresin layer 24 is placed at the position as shown in FIG. 6 when thefilm 23 is held between the molds 11 and 22 and a polycarbonate resin isinjected in a cavity.

First, as shown in FIG. 4, the fixed mold 11 and the movable mold 12 arespaced apart a certain distance, and the film 23 to which the siliconelayer 24 is printed is placed at the predetermined positiontherebetween. Next, the movable mold 12 is transferred to the directionof the arrow in FIG. 4. The movable mold 12 is moved and presses thefilm 23, and the film 23 is inserted between the fixed mold 11 and themovable mold 12.

Next, as shown in FIG. 6, a polycarbonate resin is injected into thecavity to mold a frame body 1. At this time, the silicone resin layer 24is transferred to the frame body 1 at the portion adjacent to theperipheral of the opening portion of the through hole thereof. Injectionof the polycarbonate resin is carried out by setting the nozzletemperature of about 200° C. and the mold temperature of about 80° to90° C.

The above-mentioned process is an effective method in which molding ofthe frame body 1 and formation of the silicone resin layer 24 can becarried out simultaneously. However, it can be also carried out to thestep of molding a thermoplastic resin firstly and then the step offorming a silicone resin layer at the predetermined portion of thethermoplastic resin molded product (frame body 1).

After completion of molding the frame body 1, the movable mold 12 isreturned to the original position, the winding roller 22 is rotated towind the film 23, and a new silicone resin layer is moved to thepredetermined position. Thus, when the film 23 to which the siliconeresin layers 24 are printed is previously prepared, molding of the framebody 1 and formation of the silicone resin layer can be carried outcontinuously and effectively.

Next, as shown in FIG. 7, the frame body 1 to which the silicone layer 5is formed is placed to a fixed mold 31 of a second mold 30. As shown inFIG. 8, a movable mold 32 is attached to the fixed mold 31 and a styreneseries elastomer is injected into a space portion between the fixed mold31 and the movable mold 32 to mold a button portion 2. This injection iscarried out by setting the nozzle temperature of about 170° C. to about200° C. and the mold temperature of about 30° C. to about 90° C.

At this time, the silicone resin does not fuse to the styrene serieselastomer which is a thermoplastic elastic material and remains fused tothe polycarbonate which is a thermoplastic resin. That is, according tothe above process, a composite molded product in which the flangeportion 4 of the button portion fuses to the frame body 1 but does notfuse to the silicone resin layer 5 can be manufactured.

As described above, in the composite molded product of the presentinvention, the silicone resin layer 5 is provided at the position whichis between the flange portion 4 of the button portion 2 and the framebody 1, and adjacent to the opening portion of the frame body 1. Thissilicone resin layer 5 fuses to the frame body 1 but does not fuse tothe flange portion 4 so that when the pressing portion 3 is pressed, theflange portion 4 is markedly deflected whereby a large stroke can beobtained.

Also, in the method of manufacturing the composite molded product of thepresent invention, a fusible portion and a non-fusing portion can befreely provided to the contacting surface of the thermoplastic resin andthe thermoplastic elastic material so that, for example, a compositemolded product which is applied to a button of electric devices can bemanufactured easily and effectively.

While the present invention has been described in connection withcertain preferred embodiments, it is to be understood that the subjectmatter encompassed by the present invention is not limited to thosespecific embodiments. On the contrary, it is intended to include allalternatives, modifications, and equivalents as can be included withinthe spirit and scope of the following claims.

I claim:
 1. A method of manufacturing a composite button of anelectrical device, comprising the steps of:(a) molding a frame body witha through bore that terminates at an opening in a contact surface, thecontact surface having a film area that surrounds the opening and afusion area that surrounds the film area; (b) forming a thin film layeron the film area of the contact surface; and (c) molding a buttonportion having a movable pressing portion extending within the bore anda flange which is positioned adjacent the thin film layer and the fusionarea of the frame body, wherein, as the flange is formed, fusion bondingoccurs between areas of the flange contacting the fusion areas, and nofusion bonding occurs between areas of the flange contacting the filmlayer such that the flange is separateable from the film layer anddeflectable when the button is pressed.
 2. The method of manufacturing acomposite button of an electrical device according to claim 1,comprising using a thermoplastic resin as a material for the frame body,using a thermoplastic elastic material as a material for the buttonportion and using a silicone resin layer as a material for the thin filmlayer.
 3. The method of manufacturing a composite button of anelectrical device according to claim 1, wherein the step of molding theframe body and the step of forming the thin film layer are carried outsimultaneously.
 4. The method of manufacturing a composite button of anelectrical device according to claim 1, further including the step ofproviding said thin film layer printed onto a film and transferring saidthin film layer to the frame body.
 5. The method of manufacturing acomposite button of an electrical device according to claim 1,comprising the steps of:molding the frame body by setting a moldingnozzle temperature at about 200° C. and a mold temperature in a range ofabout 80° C. to about 90° C.; and molding the button portion by settinga molding nozzle temperature in a range of about 170° C. to about 200°C. and a mold temperature in a range of about 30° C. to about 200° C.